build/pkgs/tox/spkg-configure.m4: Check for good tox 3, tox 4 version…

…s separately

build/pkgs/tox/spkg-configure.m4

@@ -1,17 +1,28 @@
 SAGE_SPKG_CONFIGURE([tox], [
        dnl Use non-ancient tox with full support for PEP 517.
-       m4_pushdef([TOX_MIN_VERSION], [3.21.4])
-       AC_CACHE_CHECK([for tox >= ]TOX_MIN_VERSION, [ac_cv_path_TOX], [
+       m4_pushdef([TOX3_MIN_VERSION], [3.21.4])
+       dnl Early 4.0.x versions have bugs regarding complex factor conditions
+       m4_pushdef([TOX4_MIN_VERSION], [4.0.15])
+       AC_CACHE_CHECK([for tox 3 >= ]TOX3_MIN_VERSION[ or tox 4 >= ]TOX4_MIN_VERSION, [ac_cv_path_TOX], [
          AC_PATH_PROGS_FEATURE_CHECK([TOX], [tox], [
             tox_version=$($ac_path_TOX --version 2> /dev/null | tail -1)
             AS_IF([test -n "$tox_version"], [
-                AX_COMPARE_VERSION([$tox_version], [ge], TOX_MIN_VERSION, [
-                    ac_cv_path_TOX="$ac_path_TOX"
-                    ac_path_TOX_found=:
+                AX_COMPARE_VERSION([$tox_version], [lt], [4], [
+                    AX_COMPARE_VERSION([$tox_version], [ge], TOX3_MIN_VERSION, [
+                        ac_cv_path_TOX="$ac_path_TOX"
+                        ac_path_TOX_found=:
+                    ])
+                ], [
+                    AX_COMPARE_VERSION([$tox_version], [ge], TOX4_MIN_VERSION, [
+                        ac_cv_path_TOX="$ac_path_TOX"
+                        ac_path_TOX_found=:
+                    ])
                 ])
             ])
          ])
        ])
        AS_IF([test -z "$ac_cv_path_TOX"],
              [sage_spkg_install_tox=yes])
+       m4_popdef([TOX4_MIN_VERSION])
+       m4_popdef([TOX3_MIN_VERSION])
 ])